This invention relates generally to air conditioning systems and, more particularly, to a method and apparatus for diagnosing faults in such a system having multiple drive motors.
As improved design and operational procedures for heating, ventilation and air conditioning (HVAC) systems are continually being provided for the benefit of users, such systems are typically becoming more complex and difficult to install and maintain. Among some of the difficulties that occur are improper wiring of the various components and the related problems which are difficult to diagnose in complex HVAC systems. For example, in a multi-zone system, wherein it is desirable to introduce varying degrees of cooling or heating to various zones in a building, a plurality of drive motors are connected to position their respective dampers in a desired position so as to regulate the degree of cooling/heating in their particular zones. In the event that one of the damper drive motors is connected improperly, a fault will occur in the system, but it is difficult to determine exactly where that fault has occurred. Accordingly, the diagnosis and repair of the problem can be unduly complicated.
One such system is a variable volume multizone system as shown and described in U.S. Pat. No. 4,630,670 assigned to the assignee of the present invention. That patent is incorporated herein by reference. As will be seen, both the fan speed and the respective damper positions are selectively varied to obtain the desired temperatures in the various zones. Other similar systems maintain a constant fan speed while varying the damper positions by individual motor control.